Hydrodesulfurization catalyst and method for preparing the same

Abstract

The application discloses a kind of hydrodesulfurization catalyst and preparation method thereof.The catalyst includes catalyst precursor and macroporous alumina layer coated on the surface of catalyst precursor, the catalyst precursor includes alumina and active component, and the total acid amount of the macroporous alumina layer is 0.500-0.800 mmol / g.The catalyst preparation method of the application includes the steps of directly kneading pseudo-boehmite with solution containing active component, forming, wrapping macroporous pseudo-boehmite after drying, and then calcining.The catalyst is applied to residue oil hydrogenation reaction, has excellent desulfurization, metal removal ability, and has good removal stability, which provides technical support for extending the operation cycle of device.

Description

TECHNICAL FIELD

[0001] The present application relates to a hydrogenation catalyst and a preparation method thereof, in particular to a hydrodesulfurization catalyst and a preparation method thereof. BACKGROUND

[0002] Residue hydrotreating technology has outstanding advantages in the upgrading and cleaning of poor-quality oil products. Residue has large viscosity, high impurity content and complex molecular composition, and it is difficult to hydrogenate. Effective removal of metal, sulfur, nitrogen and carbon residue impurities in residue through catalytic reaction requires different catalysts with different functions, shapes and sizes to be matched and packed in the system to achieve high activity and long-term operation in industry. Residue hydrotreating catalysts generally include protective catalysts, metal removal catalysts, desulfurization catalysts and denitrogenation catalysts.

[0003] At present, residue hydrodesulfurization catalysts are generally prepared by impregnating an aqueous solution containing active metal compounds into an alumina carrier or an alumina carrier containing a small amount of additives, and then drying and baking through post-treatment processes.

[0004] CN201310597246.7 discloses a poor-quality heavy oil hydrodesulfurization catalyst and a preparation method thereof. The catalyst uses alumina as a carrier and VIB and VIII elements, especially Ni-Mo, as active components. The catalyst has a pore volume of 0.45-0.60 cm 3 / g, a specific surface area of 205-260 m 2 / g, and an average pore diameter of 7.0-12.0 nm, which gradually increases from the center to the outer surface of the catalyst particle in the radial direction.

[0005] CN201510724870.8 discloses a hydrodesulfurization catalyst containing active metal components and a modified hydrogenation catalyst carrier. The modified hydrogenation catalyst carrier includes a carrier and metal additives and acid additives supported on the carrier. The metal additives and acid additives are distributed in layers on the carrier, with the first shell layer being the metal additives and the first core layer being the acid additives. The metal additives are group IA and / or group IIA metal components, and the acid additives are selected from at least one component of F, P and B.

[0006] CN201910712210.6 discloses a hydrodesulfurization catalyst, a preparation method and application thereof. The hydrodesulfurization catalyst comprises a modified catalyst carrier and supported active metals. The modified catalyst carrier is a γ-Al2O3 carrier modified by rare earth elements, or a composite carrier prepared by mixing γ-Al2O3 and an acid molecular sieve through a binder and then calcining, and then modified by rare earth elements.

[0007] The hydrogen desulfurization catalyst prepared by the above method contains active metal on the outer surface, the hydrogenation reaction on the surface of the catalyst is relatively intense, and the generated carbon deposition is easy to block the pores of the catalyst, thereby affecting the service life of the catalyst. SUMMARY

[0008] In view of the deficiencies of the prior art, the purpose of the present application is to provide a residue hydrodesulfurization catalyst and a preparation method thereof, which can significantly improve the anti-carbon deposition performance of the hydrodesulfurization catalyst, the metal capacity, and the operation cycle of the hydrogenation device.

[0009] The first aspect of the present application provides a preparation method of a hydrodesulfurization catalyst, comprising the following steps:

[0010] (1) neutralizing the acid aluminum salt solution and the basic aluminum salt solution to obtain a slurry;

[0011] (2) performing first-stage aging on the slurry obtained in step (1); after the first-stage aging, adding a water-soluble polymer A and performing second-stage aging to obtain a pseudo-boehmite gel;

[0012] (3) dividing the pseudo-boehmite gel obtained in step (2) into two parts A and B, drying A to obtain a macroporous pseudo-boehmite, and slushing B with water to obtain a macroporous pseudo-boehmite slurry;

[0013] (4) mixing and kneading the pseudo-boehmite obtained in step (3) with a solution containing an active component, a extrusion aid, and a binder, shaping, drying, to obtain a catalyst precursor;

[0014] (5) stirring and soaking the catalyst precursor obtained in step (4) in the macroporous pseudo-boehmite slurry of step (3), taking out after the surface is wrapped with the slurry, drying, and calcining to obtain the hydrodesulfurization catalyst.

[0015] In the method of the present application, in step (1), the acid aluminum salt solution and the basic aluminum salt solution are added to the reaction kettle in a parallel flow manner, and the addition time is 40-120 min.

[0016] In the method of the present application, in step (1), the acid aluminum salt is selected from one or more of aluminum sulfate and aluminum nitrate solution, and the concentration of the acid aluminum salt solution calculated based on Al2O3 is 5g / 100mL-18g / 100mL; the basic aluminum salt solution is one or more of sodium metaaluminate solution and potassium metaaluminate solution, and the concentration of the basic aluminum salt solution calculated based on Al2O3 is 15g / 100mL-45g / 100mL.

[0017] In the method, the temperature of the neutralization reaction in step (1) is 80-105℃, and the time is 40-120 min, and the pH value of the slurry is controlled to be 7.0-9.0 during the neutralization reaction. The pH value of the slurry is controlled by controlling the adding amount of the first acidic aluminum salt solution and the basic aluminum salt solution or by adding an acid-base regulator during the neutralization reaction.

[0018] In the method, the temperature of the first-stage aging in step (2) is 150-250℃, the time is 60-200 min, and the pH value is 9.0-11.0.

[0019] In the method, the water-soluble polymer A in step (2) is one or more of polyvinyl alcohol, polyethylene glycol, polyacrylamide and methyl cellulose. The adding amount of the water-soluble polymer A is that the concentration of the water-soluble polymer A in the system after adding is 1-10 g / 100 mL. The viscosity (20℃) of the system after adding the water-soluble polymer A is 100-500 mPa·s.

[0020] In the method, after the first-stage aging in step (2) is completed, the slurry is preferably concentrated first, so that the volume after the concentration is 40%-70% of the original volume.

[0021] In the method, the temperature of the second-stage aging in step (2) is 170-300℃, and the time is 45-200 min. The temperature of the second-stage aging is higher than that of the first-stage aging, preferably 20-50℃ higher.

[0022] In the method, the mass ratio of A to B in step (3) is 1:1-8:1.

[0023] In the method, the macroporous pseudoboehmite obtained in step (3) is filtered and washed before drying. The filtering and washing are conventional technical means in the art. The drying condition is 100-160℃ for 2-12 hours. The dry basis content of the macroporous pseudoboehmite after drying is 40wt%-75wt%.

[0024] In step (4), the solution containing active components is a molybdenum-nickel-phosphorus solution, and the content of molybdenum oxide in the solution is 7.0-45.0 g / 100 mL, the content of nickel oxide is 1.7-11.0 g / 100 mL, and the content of phosphorus is 0.7-4.5 g / 100 mL.

[0025] In the method, the extrusion aid in step (4) is selected from one or more of sesbania powder, cellulose (such as at least one of methyl cellulose, hydroxypropyl cellulose), and resin (such as at least one of phenolic resin or ethylene-vinyl acetate resin). The amount of the extrusion aid is 0.5% to 10% of the mass of the macroporous pseudoboehmite obtained in step (3). The binder is selected from at least one of inorganic acid or organic acid, wherein the inorganic acid solution can be nitric acid, and the organic acid solution is selected from at least one of acetic acid, citric acid, and tartaric acid. The amount of the binder is 0.1% to 15% of the mass of the macroporous pseudoboehmite obtained in step (3).

[0026] In the method, the drying condition in step (4) is 100 to 160°C for 2 to 12 hours.

[0027] In the method, the soaking time in step (5) is 3 seconds to 10 minutes. After the surface is coated with the slurry, the coated catalyst precursor is taken out and centrifuged to remove the excess solution on the surface. The centrifugation time is 1 to 20 minutes. Then, the coated catalyst precursor is dried at 100 to 160°C for 2 to 12 hours.

[0028] In the method, the content of alumina in the slurry of the macroporous pseudoboehmite in step (5) is 5 to 100 g / L.

[0029] In the method, the catalyst precursor is preferably soaked in the binder solution in step (5). The mass content of the binder in the binder solution is 1% to 80%, preferably 2% to 20%. The binder solution is composed of the binder and pure water. The binder can be one or more of starch, dextrin, polyvinyl alcohol, and carboxymethyl cellulose. The catalyst precursor is preferably soaked in the binder solution for 5 to 60 seconds, the excess binder solution is drained, and the coated catalyst precursor is left to stand at room temperature for 15 to 60 minutes.

[0030] In the method, the calcination condition in step (5) is 450 to 600°C for 2 to 6 hours, and the calcination is performed in an oxygen-containing atmosphere.

[0031] The second aspect of the present application provides a hydrodesulfurization catalyst prepared by the method of the first aspect.

[0032] In the present application, the catalyst comprises a catalyst precursor and a macroporous alumina layer coated on the surface of the catalyst precursor. The catalyst precursor comprises alumina and an active component. The total acid amount of the macroporous alumina layer is 0.500 to 0.800 mmol / g, and the total acid amount is preferably 0.525 to 0.575 mmol / g.

[0033] In the present application, the pore volume of the macroporous alumina layer is 0.85 to 1.20 cm 3The pore volume of the pores with a pore diameter of 50-100 nm is 12-50% of the total pore volume.

[0034] In the present application, the thickness of the large-pore alumina layer is 1-500 μm, preferably 50-180 μm, and further preferably 60-110 μm.

[0035] In the present application, the specific surface area of the catalyst precursor is 160-240 m 2 The pore volume is 0.55-0.76 mL / g, and preferably 0.62-0.76 mL / g.

[0036] In the present application, the active components include molybdenum, nickel and phosphorus, and the content of molybdenum oxide is 5.0-25.0% by mass, the content of nickel oxide is 1.0-6.0% by mass, and the content of phosphorus is 0.5-2.5% by mass, based on the mass of the catalyst precursor.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1. The hydrogenation desulfurization catalyst of the present application comprises a precursor and a large-pore alumina layer coated on the surface of the catalyst precursor, and the active components are not contained in the large-pore alumina, so that the intensity of the hydrogenation reaction on the surface can be reduced. Since the outer surface has a certain acidity, the residue oil undergoes partial hydrogenation reaction and thermal cracking, and the coke produced is first deposited in the pore channels of the alumina on the surface. Since the outer surface of the catalyst is coated with large-pore alumina, the coke deposition does not block the pore channels, and the residue oil can enter the interior of the catalyst body to undergo hydrogenation reaction, so that the catalyst has good metal capacity, anti-coking performance and stability.

[0039] 2. The hydrogenation desulfurization catalyst of the present application is prepared by directly kneading pseudo-boehmite and a solution containing active components, shaping, wrapping the large-pore pseudo-boehmite after drying, and then calcining. The method of the present application not only saves the calcination process of the carrier and reduces the energy consumption for preparing the catalyst, but also the outer surface of the catalyst prepared finally is a large-pore alumina layer not containing active components. Compared with the conventional hydrogenation desulfurization catalyst, the intensity of the hydrogenation reaction on the surface is reduced, and the surface layer has a certain acidity and a large pore diameter, so that the metal capacity, anti-coking performance and removal stability of the catalyst are improved. DETAILED DESCRIPTION

[0040] The technical solutions and effects of the present application will be further illustrated by the following examples. The examples are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0041] In the present application, the method for measuring the total acid amount of the macroporous alumina layer is as follows: the macroporous alumina on the outer surface of the calcined catalyst is scraped off, then tabletting is performed, and then the instrument AUTOCHEM 2910 programmed temperature adsorption instrument is used to perform nitrogen blowing at room temperature, dehydration by temperature rising, ammonia gas passing at a set temperature, sample adsorption to ammonia gas saturation, then nitrogen blowing to remove the physically adsorbed ammonia gas on the surface of the sample, and finally NH3 adsorbed on the sample is desorbed under the condition of programmed temperature rising, and the acid amount is obtained by calculating the area of the desorption peak.

[0042] In the present application, the pore volume and specific surface area of the catalyst precursor involved in the examples and comparative examples are tested by using the American Micromeritics TriStar 2420 physical adsorption analyzer after the macroporous alumina on the outer surface of the calcined catalyst is scraped off. The pore volume (mercury injection) of the outer surface macroporous alumina involved in the examples and comparative examples is tested by using the American CANTA instrument company PoreMaster60GT mercury injection apparatus. The specific surface area of the outer surface macroporous alumina involved in the examples and comparative examples is tested by using the American Micromeritics TriStar 2420 physical adsorption analyzer.

[0043] In the present application, the metal element content in the solution and catalyst in the examples and comparative examples is obtained by inorganic analysis.

[0044] Example 1

[0045] (1) 2L of an aqueous aluminum sulfate solution (concentration of Al2O3 is 10.5g / 100mL, initial temperature is 85℃) is introduced into a reaction kettle equipped with a 5L clean water stirring device and a heating jacket from the upper part, 1.5L of an aqueous sodium aluminate solution (concentration of Al2O3 is 32.3g / 100mL, initial temperature is 90℃) is introduced into the reaction kettle from the bottom of the kettle, and the neutralization reaction temperature is controlled at 90℃; the aluminum sulfate solution and the sodium aluminate solution are continuously added, and the pH value is controlled at 8.4, and the slurry is obtained after being stabilized for 50 minutes;

[0046] (2) The slurry obtained in step (1) is subjected to first stage aging, the aging temperature is 155℃, the aging time is 120 minutes, and the pH value is 9.2; after the first stage aging is completed, the slurry is concentrated to 5L, 100g of polyvinyl alcohol is added, the viscosity (20℃) of the system slurry is 310mPa·s, the temperature is raised to 180℃, and the second stage aging is performed for 120 minutes to obtain a macroporous pseudoboehmite gel;

[0047] (3) The pseudo-boehmite gel obtained in step (2) is divided into A and B parts with a mass ratio of 2:1, A part is filtered, washed, and dried at 120°C for 4h to obtain pseudo-boehmite;

[0048] (4) A 200ml molybdenum-nickel-phosphorus solution is prepared, the content of molybdenum oxide in the solution is 19.8g / 100ml, the content of nickel oxide is 4.6g / 100ml, and the content of phosphorus is 2.0g / 100ml. 320g of pseudo-boehmite is mixed with the molybdenum-nickel-phosphorus solution, 5g of sesbania powder, 10g of methyl cellulose, and 4g of nitric acid are added, and pure water is kneaded to form a catalyst precursor, which is dried at 110°C for 5 hours to obtain a catalyst precursor;

[0049] (5) A binder solution is prepared by dissolving 20g of dextrin in 400g of pure water. The catalyst precursor is soaked in the binder solution for 10 seconds, then taken out and the excess binder solution is drained. It is placed at room temperature for 40 minutes. Then, it is added to the macroporous pseudo-boehmite slurry (alumina content of 74g / L) and stirred for 1 minute. After the surface is coated with the slurry, it is taken out and centrifuged for 5 minutes using a high-speed centrifuge. It is then dried at 110°C for 5 hours. It is calcined at a temperature of 500°C with a heating rate of 2°C / min for 4 hours to obtain a hydrodesulfurization catalyst A.

[0050] Example 2

[0051] The same as example 1, except that the neutralization reaction temperature in step (1) is controlled at 95°C to prepare a hydrodesulfurization catalyst B of the present application.

[0052] Example 3

[0053] The same as example 1, except that in step (5), after being added to the macroporous pseudo-boehmite slurry, it is stirred and then centrifuged for 7 minutes using a high-speed centrifuge to obtain a hydrodesulfurization catalyst C.

[0054] Example 4

[0055] The same as example 1, except that in step (5), the macroporous pseudo-boehmite slurry is diluted (alumina content of 46g / L), and the catalyst precursor is added to the diluted macroporous pseudo-boehmite slurry to obtain a hydrodesulfurization catalyst D.

[0056] Example 5

[0057] The same as example 4, except that in step (5), after being added to the macroporous pseudo-boehmite slurry, it is stirred and then centrifuged for 8 minutes using a high-speed centrifuge to obtain a hydrodesulfurization catalyst E.

[0058] Comparative Example 1

[0059] The same as Example 1, except that the catalyst precursor obtained in step (4) is directly calcined at 500°C for 4 hours to obtain a hydrodesulfurization catalyst F.

[0060] Comparative Example 2

[0061] An industrial pseudo-boehmite, 2 wt% nitric acid and 2 wt% of the sesbania powder are mixed, molded, dried at 130°C for 3 hours and calcined at 700°C for 3 hours to prepare an alumina carrier (carrier saturated water absorption rate is 0.90). The carrier is saturatedly impregnated with a molybdenum-nickel-phosphorus-containing impregnation solution (wherein the content of molybdenum oxide is 19.8 g / 100 mL, the content of nickel oxide is 4.6 g / 100 mL, and the content of phosphorus is 2.0 g / 100 mL), dried at 120°C for 5 hours and then calcined at 500°C for 4 hours to prepare a hydrodesulfurization catalyst G.

[0062] Physical and chemical properties of the catalysts obtained in Examples 1-5 and Comparative Examples 1-2

[0063]

[0064] Evaluation test

[0065] The hydrodesulfurization catalysts prepared in Examples 1-5 and Comparative Examples 1-2 are used to treat a residue oil under the same process conditions. The properties of the residue oil are shown in Table 2. A fixed bed process is used, and the process conditions for evaluation are shown in Table 3. The removal rates of each catalyst after 100 hours of operation are shown in Table 4, based on the removal rate of catalyst G.

[0066] Properties of the raw oil in Table 2

[0067] Feed properties Middle East Resid S, wt% 3.98 CCR, wt% 9.37 Ni+V, μg / g 113.7 Ni, μg / g 31.2 V, μg / g 82.5

[0068] Process conditions for evaluation in Table 3

[0069] Reaction conditions Parameter Temperature, °C 380 Pressure, MPa, 15.0 H2 / oil volume ratio 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 650:1 Liquid hourly space velocity, h -1 ]] 1.0

[0070] Removal rates after operation in Table 4

[0071]

[0072] Removal rates after operation in Table 4 (continued)

[0073]

[0074] As can be seen from Table 4, the hydrodesulfurization catalysts prepared in the present application have better desulfurization and demetallization performance than the comparative catalysts, and have good removal stability, which provides technical support for extending the operation period of the device.

Claims

1. A process for preparing a hydrodesulfurization catalyst, characterized by, The hydrodesulfurization catalyst comprises a catalyst precursor and a macroporous alumina layer coated on the surface of the catalyst precursor, and the macroporous alumina layer has a thickness of 50-180 μm; and the preparation method of the hydrodesulfurization catalyst comprises the following steps: (1) neutralization reaction of an acidic aluminum salt solution and an alkaline aluminum salt solution to obtain a slurry; (2) first-stage aging of the slurry obtained in step (1); after the first-stage aging, a water-soluble polymer A is added, and second-stage aging is performed to obtain a pseudo-boehmite gel; (3) the pseudo-boehmite gel obtained in step (2) is divided into two parts A and B; A is dried to obtain a macroporous pseudo-boehmite; and B is slurried with water to obtain a macroporous pseudo-boehmite slurry; (4) mixing, molding, drying and the like of the pseudo-boehmite obtained in step (3) with a solution containing an active component, a extrusion aid and a binder to obtain a catalyst precursor; (5) stirring and soaking of the catalyst precursor obtained in step (4) in the macroporous pseudo-boehmite slurry obtained in step (3), taking out after the surface is coated with a gel, drying and calcining to obtain the hydrodesulfurization catalyst; In step (1), the pH value of the slurry is controlled to be 7.0-9.0 during the neutralization reaction; In step (2), the pH value of the first-stage aging is 9.0-11.0; In step (2), the temperature of the first-stage aging is 150-250 ℃; In step (2), the temperature of the second-stage aging is 170-300 ℃; The temperature of the second-stage aging is 20-50 ℃ higher than that of the first-stage aging.

2. The production method according to claim 1, characterized by, In step (1), the acidic aluminum salt solution and the alkaline aluminum salt solution are subjected to a parallel flow neutralization reaction; the acidic aluminum salt is selected from one or more of aluminum sulfate and aluminum nitrate solution; the concentration of the acidic aluminum salt solution, calculated based on Al2O3, is 5 g / 100 mL-18 g / 100 mL; and the alkaline aluminum salt solution is one or more of sodium metaaluminate solution and potassium metaaluminate solution, and the concentration of the alkaline aluminum salt solution, calculated based on Al2O3, is 15 g / 100 mL-45 g / 100 mL.

3. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the neutralization reaction is 80-105 ℃, and the time is 40-120 min.

4. The method of claim 1, wherein, In step (2), the time of the first-stage aging is 60-200 min; and / or, the time of the second-stage aging in step (2) is 45-200 min.

5. The preparation method according to claim 1, characterized in that, In step (2), the water-soluble polymer A is one or more of polyvinyl alcohol, polyethylene glycol, polyacrylamide and methyl cellulose; the concentration of the water-soluble polymer A is 1-10 g / 100 mL; and the viscosity of the system after the addition of the water-soluble polymer A is 100-500 mPa·s.

6. The method of claim 1, wherein, In step (2), after the first-stage aging is completed, the slurry is first concentrated so that the volume after the concentration is 40%-70% of the original volume.

7. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of A to B is 1:1-8:

1.

8. The method of claim 1, wherein, In step (3), the dry content of the macroporous pseudo-boehmite obtained after the drying is 40 wt%-75 wt%.

9. The method of claim 1, wherein, In step (4), the solution containing active components contains 7.0-45.0 g / 100 mL of molybdenum oxide, 1.7-11.0 g / 100 mL of nickel oxide and 0.7-4.5 g / 100 mL of phosphorus.

10. The method of claim 1, wherein, In step (5), the catalyst precursor is soaked in the binder solution before being stirred and soaked in the macroporous pseudo-boehmite, the soaking time is 5-60 seconds, the excess binder solution is drained, and the mixture is left to stand at room temperature for 15-60 minutes.

11. The method of claim 1, wherein, In step (5), the content of alumina in the macroporous pseudo-boehmite slurry is 5-100 g / L.

12. The method of claim 1, wherein, In step (5), the soaking time is 3 seconds-10 minutes, the surface is wrapped with the gel, the surface is removed by centrifugation, the centrifugation time is 1-20 minutes, and then the mixture is dried at 100-160 ℃ for 2-12 hours.

13. The method of claim 1, wherein, In step (5), the calcination condition is that the mixture is calcined at 450-600 ℃ for 2-6 hours, and the calcination is carried out in an oxygen-containing atmosphere.

14. The hydrodesulfurization catalyst prepared by the method of any one of claims 1-13.

15. The catalyst of claim 14, wherein The catalyst comprises a catalyst precursor and a macroporous alumina layer coated on the surface of the catalyst precursor, the catalyst precursor comprises alumina and active components, and the total acid amount of the macroporous alumina layer is 0.500-0.800 mmol / g.

16. The catalyst of claim 14, wherein The total acid amount of the macroporous alumina layer is 0.525-0.575 mmol / g.

17. The catalyst of claim 15, wherein The large-pore alumina layer has a pore volume of 0.85 to 1.20 cm 3 / g, and the pore volume of the pores having a pore diameter of 50 to 100 nm accounts for 12% to 50% of the total pore volume.

18. The catalyst of claim 15, wherein, The thickness of the macroporous alumina layer is 50-180 μm.

19. The catalyst of claim 15, wherein The thickness of the macroporous alumina layer is 60-110 μm.

20. The catalyst of claim 15, wherein, The active components comprise molybdenum, nickel and phosphorus, the content of molybdenum oxide is 5.0%-25.0% based on the mass of the catalyst precursor, the content of nickel oxide is 1.0%-6.0% based on the mass of the catalyst precursor, and the content of phosphorus is 0.5%-2.5% based on the mass of the catalyst precursor.

21. The catalyst of claim 15, wherein, The specific surface area of the catalyst precursor is 160 to 240 m 2 / g, and the pore volume is 0.55 to 0.76 mL / g.

22. The catalyst of claim 15, wherein, The pore volume of the catalyst precursor is 0.65-0.76 mL / g.

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